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Since the discovery of aggregation-induced emission (AIE), the development of new AIE fluorogens (AIEgens) has become a significant field owing to their versatile application in diverse fields. To achieve aggregation-caused quenching (ACQ) to AIE conversion, considerable attention is paid to the strategy of changing the stacking pattern of molecules, and several researchers are focused on modulating the electronic structure of the excited state of molecules. In this study, acetoxy and methoxy electron-donating groups (EDG) and carboxyl and ester electron-withdrawing groups (EWG) were introduced onto quinoline through a facile Suzuki coupling reaction. The experimental results reveal that the behavior of quinoline derivatives can be converted from ACQ to AIE by altering substituents from EDG to EWG. Single-crystal X-ray diffraction (SCXRD) and transient and steady-state spectra were employed to reveal that their AIE mechanism involved the restriction of intramolecular motion (RIM). In addition, density functional theory (DFT) calculations showed that the ACQ to AIE transition can be achieved by changing the reorganization energy distribution of the molecule with different substituents in the excited state. Furthermore, the coordination of quinoline nitrogen atoms to Fe3+ facilitated the production of larger nanofibers that possessed enhanced AIE properties. This unique characteristic was utilized to leverage the capabilities of methyl 4-(quinolin-5-yl)benzoate (5-MQB) as a ratiometric fluorescent probe for detecting Fe3+ in aqueous solution. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes. However, most of them have poor robustness in aqueous solution due to competitive coordination effects between water molecules and central metal ions. Herein, a copper-based MOF (Cu-SM MOF) was prepared using copper ions and 5-(sulfomethyl) isophthalic acid (5-SMIPA) by a hydrothermal process. Considering the similarity of coordination and morphology with HKUST-1, the aqueous stability and laccase-like activity of the Cu-SM MOF were investigated using HKUST-1 as the reference. The Cu-SM MOF shows superior aqueous stability to HKUST-1 after immersion in buffer solutions, especially under alkaline conditions. Moreover, the Cu-SM MOF possesses higher catalytic activity than HKUST-1 at a high salt concentration, high temperature, etc., because the Cu-SM MOF exhibits lower Km and higher Vmax values than those of laccase and reported mimetic enzymes. The mimetic enzyme behavior of the Cu-SM MOF is demonstrated in the oxidation of phenols, as well as in the detection of 2,4-dichlorophenol (2,4-DP) and p-nitrophenol with linear ranges of 1–100 μM and 2–250 μM, and limits of detection of 0.53 μM and 1.62 μM, respectively. Owing to the excellent aqueous stability and laccase-like activity of the Cu-SM MOF, it has great application prospects in many fields, such as the determination of phenols and the treatment of industrial wastewater. [ABSTRACT FROM AUTHOR]

Ultralong room-temperature phosphorescence materials with photostimulus-responsive (named URTP-PSR) behaviour are amazing but still rarely reported due to their great limitations in the crystal structure, complicated synthesis process, slow photo-activation and deactivation. Herein, a series of URTP-PSR materials, named BADs@BA, were prepared by a facile doping process, which involved one-pot heat treatment of benzoic acid derivatives and boric acid. The BADs@BA displayed gradually enhanced ultralong phosphorescence upon prolonged deep UV light irradiation under ambient conditions. The photo-activation and deactivation process could be finished within several seconds, which was much faster than those of the previously reported URTP-PSR materials. The optical process could be repeated many times without losing performance, suggesting excellent fatigue resistance behaviours of the BADs@BA. Owing to their high processability and URTP-PSR behaviour, the BADs@BA can be utilized for anti-counterfeiting pattern applications. It is worth mentioning that all of the raw materials are commercialized and of low-cost, and could be purchased directly, which is of benefit for practical applications. These findings could break through many limitations of existing dynamic RTP materials and expand the scope of dynamic smart-response materials for great potential in many fields. [ABSTRACT FROM AUTHOR]

Since the concept of aggregation-induced emission (AIE) was proposed, along with the development of new AIE molecules and broadening of its application field, the exploration of its mechanism has attracted more and more attention. During the past years, various mechanisms have been proposed to reveal this novel phenomenon, including restriction of intramolecular motion (RIM) and restriction of access to the dark state (RADS). However, most of the studies have been focused on the effect of molecular structures and their stacking mode on their AIE behavior, and little effort has been made to reveal the role of the interaction between solvent and AIE aggregates on it. Herein, a series of AIE molecules have been designed and synthesized by introducing the carbonyl group into different aromatic rings, since it possesses a good spin–orbit coupling (SOC) effect and hydrogen bond acceptor, which could allow the molecules to enter the dark state. The solvent effect on their fluorescence properties and excited state electronic structures was investigated by using transient and steady state spectra, X-ray single crystal diffraction spectra and density functional theory (DFT) calculations. It was found that the water molecules not only acted as the poor solvent to induce the significant aggregation and inhibit the nonradiative transition but also as the hydrogen bond donor to induce the RADS process for triggering fluorescence. Moreover, owing to the unique intermolecular hydrogen bond effect on its fluorescence behavior, the 4-(quinolin-8-yl) benzaldehyde (QLB-8) molecule had been applied to the detection of aspartic acid. These results not only clarify the role of hydrogen bonding in AIE properties, but also provide new ideas to further design AIE molecules. [ABSTRACT FROM AUTHOR]

A novel luminescent metallacage was prepared by coordinating silver with benzimidazole tetraphenylethylene. It possesses high stability and strong fluorescence not only in dilute solutions but also in the aggregated state. [ABSTRACT FROM AUTHOR]

The intermolecular interactions and molecular packing form of fluorescent molecules have a huge impact on their optical properties, especially for AIE molecules. As a class of typical AIE molecules, tetraphenylethene (TPE) and its derivatives have prominent optical properties; nevertheless, separation of mixtures of E/Z isomers is a great challenge. Herein, a series of aromatic-substituted TPE derivatives were synthesized and used to separate mixtures of E/Z isomers by common column chromatography with high yields, as confirmed by single crystal analysis, mass spectrometry and NMR spectroscopy. The structure–property relationships of these molecules were systematically investigated by a combination of spectroscopic methods, theoretical calculations and single crystal data analysis. E/Z isomers exhibit many different fluorescent properties, such as AIE and mechanochromic behavior. Moreover, the position of N on the substituted pyridine ring also has an effect on the molecule stack pattern and the fluorescent properties. Collectively, our findings could not only improve the fundamental understanding of the cis/trans isomerization and photophysical properties of TPE derivatives but also provide a good strategy for designing different substituted groups that can produce various functions and have more potential applications. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a class of crystalline porous materials utilized in various potential applications. However, the development of hollow-structured COFs with defined morphology is important for their further applications, which is rare. Herein, COF with unique hollow shuttle morphology was prepared by a Schiff condensation reaction between 4-(4-aldehyde phenyl)ethylene (TPE) and tetra-(4-aminophenyl) porphyrin (TAP). A detailed mechanistic investigation reveals that an initial self-assembly followed by a similar inside–out Ostwald ripening process is responsible for the hollow capsule formation. The hollow microshuttle-shaped capsule COF is used for studying hemoglobin adsorption, which shows an uptake of 550.82 mg g−1 of hemoglobin. These studies could foreshadow new avenues for the development of porous materials with defined morphologies for the adsorption of biomolecules. [ABSTRACT FROM AUTHOR]

Enzyme-mimicking nanomaterials (nanozymes) have been used to catalyze enzyme-like reactions for various applications. Despite these favorable properties, peroxidase-mimicking nanozymes suffer from the optimum reaction occurring in acidic solutions, which greatly limits their applications in biological systems. Herein, we demonstrate that copper Metal–Organic Polyhedra (Cu-MOP) nanorods exhibit high peroxidase-mimicking activity at a physiological pH value. Cu-MOP nanorods catalyze the generation of strong chemiluminescence signals in the presence of luminol/H2O2 and the oxidation of 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate acid) (ABTS) by H2O2 produces a green color reaction in a neutral pH solution. The Cu-MOP nanorod driven generation of color reactions is applied to develop a H2O2 sensor, and furthermore is implemented to develop a glucose detection platform. [ABSTRACT FROM AUTHOR]

Uric acid (UA) deposition in human body is very harmful, since it may induce gout. Therefore, it would be of great significance to catalyze the degradation of UA in human body. Herein, platinum nanoparticles (PtNPs) were found to be an effective mimic of uricase in the oxidation of UA. PtNPs could lower the activation energy of UA oxidation (i.e., from 139.49 kJ mol−1to 61.73 kJ mol−1), and thus increase the reaction rate constant dramatically (e.g., by the catalysis of 2.63 mg L−1PtNPs, the reaction rate constant of UA degradation at 37 °C was 5.85 × 10−4s−1, which was almost 29000 times higher than that of without PtNPs (2.02 × 10−8s−1)). Effects of degradation conditions, such as the concentration and size of PtNPs, concentration of dissolved oxygen and pH value of the solution on the catalytic degradation of UA have been studied. Furthermore, products of UA degradation were analyzed by GC-MS spectroscopy and FT-IR spectrometry. On this basis, a detailed mechanism was finally proposed for the PtNPs-catalyzed UA degradation. [ABSTRACT FROM AUTHOR]

Strong electrochemiluminescence signals caused by the highly effective electron transfer process between SnO nanoparticles-deposited multiwall carbon nanotubes (SnO NPs@MWCNTs) composite and Ru(bpy)33쇪 observed. [ABSTRACT FROM AUTHOR]

Three copper iodide coordination polymer (CuI-p-DPA) isomers were prepared from the fluorescent organic ligand p-DPA and cuprous iodide (CuI) under different solvothermal conditions, which exhibited quenched fluorescence behaviors after forming coordination polymers (CPs). These CuI-p-DPA isomers showed discrepant fluorescence responses to thiophanate-methyl (TM). Among these CuI-p-DPA isomers, α-CuI-p-DPA exhibited the maximum fluorescence enhancement after its incubation with TM in aqueous solution. The fluorescence enhancement mechanism was that TM competed with the ligand p-DPA to coordinate with CuI clusters, and then α-CuI-p-DPA released p-DPA into the solution and induced fluorescence enhancement. The present detection method possesses the advantages of good selectivity, high sensitivity, short response time, and strong anti-interference ability with a linear range of 0.5-100 μM and a detection limit of 0.01 μM. This study not only reveals that the spatial structures of CPs play an important role in the fluorescence response ability, but also provide a new fluorescence signal-on analysis method to rapidly and sensitively determine the pesticide residue for TM.

Metal-organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes. However, most of them have poor robustness in aqueous solution due to competitive coordination effects between water molecules and central metal ions. Herein, a copper-based MOF (Cu-SM MOF) was prepared using copper ions and 5-(sulfomethyl) isophthalic acid (5-SMIPA) by a hydrothermal process. Considering the similarity of coordination and morphology with HKUST-1, the aqueous stability and laccase-like activity of the Cu-SM MOF were investigated using HKUST-1 as the reference. The Cu-SM MOF shows superior aqueous stability to HKUST-1 after immersion in buffer solutions, especially under alkaline conditions. Moreover, the Cu-SM MOF possesses higher catalytic activity than HKUST-1 at a high salt concentration, high temperature, etc. , because the Cu-SM MOF exhibits lower K m and higher V max values than those of laccase and reported mimetic enzymes. The mimetic enzyme behavior of the Cu-SM MOF is demonstrated in the oxidation of phenols, as well as in the detection of 2,4-dichlorophenol (2,4-DP) and p -nitrophenol with linear ranges of 1-100 μM and 2-250 μM, and limits of detection of 0.53 μM and 1.62 μM, respectively. Owing to the excellent aqueous stability and laccase-like activity of the Cu-SM MOF, it has great application prospects in many fields, such as the determination of phenols and the treatment of industrial wastewater.

The detection of Ag + in the environment is very important to determine the level of pollution from silver complexes, which have caused various human health problems. Herein, an aggregation-induced emission (AIE) chromophore (tetraphenylethane, TPE) attached to a benzimidazole group (tetra-benzimidazole, TBI-TPE) is synthesized and utilized to detect Ag + in the environment. The strong chelating effect between the benzimidazole group and Ag + leads to the formation of aggregates, and strong yellow fluorescence signals were observed after adding Ag + into a TBI-TPE solution. The stoichiometry of the complex of TBI-TPE and Ag + was established to be 1 : 2 using photochemical and mass spectra measurements. The detection limit of the Ag + assay is 90 nM with a linear range from 100 nM to 6 μM. This study provides a facile method to determine Ag + in real environmental samples with satisfactory results., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Recently, metal-selective fluorescent chemosensors have attracted intense attention for their simple and real-time tracking of metal ions in environmental samples. However, most of the existing fluorescent sensors are one-off sensors and thus suffer from large amount of reagent consumption, significant experimental cost and raising the risk of environmental pollution. In this paper, we developed a green (low reagent consumption, low-toxicity reagent use), recyclable, and visual sensor for Cu(2+) in aqueous solution by using a fluorescent gold nanoclusters membrane (FGM) as the sensing unit, basing on our findings on gold nanoclusters (Au NCs) that the bovine serum albumin (BSA)-coated Au NCs exhibit excellent membrane-forming ability under the isoelectric point of BSA, and thus enable us to obtain a new type of sensing membrane (i.e. FGM) by denaturing Au NCs; the fluorescence of FGM can be significantly quenched by Cu(2+) ion, and the quenched fluorescence can be totally recovered by histidine; the as-prepared FGM is very stable and recyclable, which makes it an ideal sensing material.

It was found that stannous chloride (SnCl(2)), as a popular inorganic reducing reagent, could obviously enhance the electrochemiluminescence (ECL) of tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)(3)(2+)) in aqueous solution. Some factors affecting the ECL reactions between Ru(bpy)(3)(2+) and Sn(2+), including pH, concentrations of coreactant, and electrode materials, were investigated by comparison with a classic ECL coreactant tripropylamine (TPA). The Ru(bpy)(3)(2+)-Sn(2+) ECL coreactant system produces stronger and more stable ECL signals, can keep its excellent ECL activity over a wider pH range and has more choices in using electrode materials than the Ru(bpy)(3)(2+)-TPA ECL coreactant system. The ECL mechanism of the Ru(bpy)(3)(2+)-Sn(2+) coreactant system was also studied in detail.